Facile preparation and characterization of sodium alginate/graphite conductive composite hydrogel

Conductive composite hydrogels based on sodium alginate (SA) and graphite were fabricated by a facile method via dispersing homogeneously conductive graphite into SA hydrogel matrix. The hydrogel was formed by in situ release of Ca²⁺ from Ca–EDTA, thus eliminating the multistep reactions and tedious purification compared to the previous work. Raman spectra, scanning electron microscopy (SEM), X‐ray diffraction (XRD), and thermogravimetric analysis (TGA) were used to characterize the structure, crystalline nature, and thermostability of SA/graphite composite hydrogels. The SA/graphite composite hydrogels exhibited the improved network and layer‐type structure. The thermal stability of the hydrogel decreased slightly after the graphite was incorporated into the SA hydrogel matrix regardless of the content of graphite. The enhanced mechanical strength of SA/graphite composite hydrogel was achieved via increasing the f value (i.e., [Ca²⁺]/[COO^‐ in alginate]) and lowering graphite content. The conductivity of the composite hydrogels could be varied in a broad range, reaching up to 10⁻³ S/cm, mainly depending on the content of graphite and the f value. POLYM. COMPOS., 37:3050–3056, 2016. © 2015 Society of Plastics Engineers